<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <div id="app">
        {{ date | formatDate}}
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue"></script>
    <script>
        //在月份、日期、小时等小于10时前面补0
        var padDate = function(value){
            return value < 10 ? '0' + value:value;
        };

        var app = new Vue({
            el:'#app',
            data:{
                date:new Date()
            },
            filters:{
                formatDate:function (value){          //这里的value就是需要过滤的数据
                    var date = new Date(value);
                    var year = date.getFullYear();
                    var month = padDate(date.getMonth() + 1);
                    var day = padDate(date.getDate());
                    var hours = padDate(date.getHours());
                    var minutes = padDate(date.getMinutes());
                    var seconds = padDate(date.getSeconds());
                    //将整理好的数据返回出去
                    return year+'-'+month+'-'+day+' '+hours+':'+minutes+':'+seconds;
                }
            },
            mounted:function(){
                var _this = this;       //声明一个变量指向Vue实例this，保证作用域一致
                this.timer = setInterval(function(){
                    _this.date = new Date();      //修改数据date
                },1000);
            },
            beforeDestroy:function(){
                if (this.timer){
                    clearInterval(this.timer)      //在Vue实例销毁前，清除我们的定时器
                }
            }
        })
    </script>
</body>
</html>